Petroleum pipeline drag reducing agents (hereafter referred to as DRA) were first commercially introduced to the world's petroleum pipeline industry in the late 1970's. The first commercially viable DRA products were produced by adding lower alpha olefin monomers having carbon ranges from C-4 to C-14 with various solvents or distillates such as heavy aromatic distillates (HAD), Mollenex raffinate, and other kerosine distillate cuts and polymerizing these olefin monomers within this mixture. A conventional Ziegler-Natta catalyst system was used to promote this polymerization process. These first commercially viable DRA products were a result of polymerizing these monomers.
The monomers were polymerized into a very high molecular amorphous polymer within a reactor purged with nitrogen gas about 99.99% pure, and being otherwise absent of moisture, and free of water and oxygen. The resulting polymerized alpha-olefin polymer constituted nominally 5-10 weight percent of the total mass of the DRA product with the solvent contributing the remainder of the mass of this type of DRA product. The physical properties of this polymerized mixture of olefin and the solvent was very viscous and soon took on the name of a DRA “GEL” product because of its apparent physical property. This DRA product was first commercially used in the Trans-Alaskan Pipeline System (“TAPS”) in the late 1970's and coincided with the ability to successfully start-up this new pipeline system. The DRA product provided immediate benefits for the TAPS. The DRA product allowed the passage of significantly larger volumes of North Slope crude oil than had been envisioned by the design standards of TAPS. The use of this DRA product allowed TAPS to overcome the impact of an unanticipated and unfortunate start-up event and further allowed TAPS to move a higher volume of crude oil without the addition and associated expense of more intermediate pumping stations originally anticipated as a requirement within the original design of this pipeline system prior to the implementation of the DRA GEL Products. From the beginning, TAPS has continuously applied DRA. Even in the evolving commercial forms of DRA, TAPS has applied DRA to its pipeline system from it's commissioning until today to move crude oil from the North Slope production area to the export terminal near Valdez, Ak. This historical use by TAPS first defined the practical and technical advantages of DRA products and was the beginning of recognizing DRA products and DRA technology as a new and “strategic component” to facilitate the ability to transport more petroleum liquids including crude oil, refined products, and natural gas liquids in existing and new pipelines used around the world.
The first DRA GEL products, as noted above, were both effective and were responsible for escorting this technology and the ultimate acceptance of the DRA product within the petroleum pipelines systems throughout the worldwide. These GEL-type DRA, however, were not a complete solution to the end-users needs. Their physical properties, price, logistical requirements and limited polymer concentration restricted their acceptance and usage within many candidate pipelines around the world. The GEL-type DRA gelatinous nature made them unhandy and troublesome in meeting application and housekeeping requirements. The operators directly involved with the application of these GEL-type DRAs had many reasons not to like the products. The operators had problems with the form and nature of the GEL-type DRAs associated with “hook-up” and the packing leakage from packing glands on DRA pumps used to inject this DRA into the high pressure petroleum was a never-ending and unpleasant chore. The physical properties of the GEL-type DRAs created daily housekeeping challenges that involved the need for the operator to physically remove this leakage from the area and dispose of the material. Proper disposal posed a secondary but significant problem.
The GEL DRA had additional usage drawbacks. The GEL DRA had inherently poor kinetic solubility characteristics and slow dissolution rates which required them to be injected through a specially configured quill assembly to help increase their dissolution rate into the petroleum pipeline stock. The use of these GEL DRA also required the use of a high-pressure gas nitrogen cylinder for low pressure regulation of nitrogen gas to supply each GEL DRA usage location the means to pressurize the DRA shipping and storage containers. The use of the high-pressure nitrogen gas promoted the movement of this thick GEL DRA product from the storage tanks to the DRA injection pump suction lines. The nitrogen pressurization requirement of the thick GEL DRA product within these shipping and storage containers was both expensive and created continuous maintenance and logistic and supply problems for the pipeline operations and other personnel. For example, the nitrogen pressurization requirement of the thick GEL DRA product required that the nitrogen gas cylinders be transported to remote locations of use such as the pump stations along the TAPS pipeline system. Other downsides included freight, logistics and inventory costs associated with these low polymer solids, GEL-based DRA solution polymers.
During the 1980's and early 1990's, these GEL DRA products found broad acceptance for use in onshore and offshore crude oil pipeline applications and were also accepted for use in refined products pipeline within the United States. The rapid expansion and use of GEL DRA in overseas locations exposed their “practical downside.” The downside related directly to their handling concerns and the logistics, transportation and container cost required with supplying large volumes of low-polymer solids GEL DRA products. Several of the offshore locations could require from several hundred to several thousand gallons of the GEL DRA products on a daily basis. Since these GEL DRA products were produced exclusively within the United States, and by only two manufacturers, and supplied to the worldwide user base from these two U.S. manufacturing locations, the need to increase the polymer solids loading per unit volume became a more serious interest and challenge.
In the mid-1990's, a new DRA product was developed which raised the polymer solids loading by a factor approaching 3-times—from nominally about 8-9% by weight to approaching 25% by weight within the same unit volume. This new high polymer solids DRA product was first produced commercially as a cryogenically-ground slurry. This slurry DRA product immediately gained worldwide user acceptance based on its superior performance advantages and logistical benefits. These slurry-based DRA products now dominate the worldwide DRA “user” markets.
However, the present DRA products have failed to completely overcome the problem of separation between suspending agents and DRA polymer solids. Further, the present water-based slurry DRA products must be specifically reformulated to meet the climatic requirements for application in arctic conditions.
The present DRA products have a limited number of usable. DRA suspending liquids. Further, many of the DRA suspending agents require special additives, such as by way of example, clays, surfactants, biocides, anti-freeze, etc.
Since the first use of DRAs and even to this day, DRA slurries must be routinely stirred or circulated to keep the finely divided polymer solids in suspension. Thus, transportation and storage remains a concern and problem with the present DRA products. Most of the present DRA slurry products often require storage and transportation within tankage equipped with exterior insulation and heat transfer exchanger equipment. The present DRA products require storage and transportation equipment that must be heated. Also, the present DRA products require specially insulated, on-site injection equipment that must be heated or cooled and mechanically more robust to operate in arctic conditions. Also, the transportation equipment must have heavy, expensive mixing and circulating devices. The heavy, expensive mixing and circulating devices require more initial capital investment and result in extra energy and fuel cost for transporting this additional mixing equipment. Further, workers must use hazardous procedures to climb on the storage and transportation equipment to use high pressure lancing and mixing equipment to attempt to remix the suspension liquid and solid polymer to re-constitute the DRA slurry. This raises safety and economic issues.
In some formulations, the present DRA slurry products have noxious odors created by the use of the non-solvents, glycol ethers and alcohols. And, the present DRA products have a higher cost when compared to using the lower temperature freeze point vegoils.
The DRA slurry-based products' “scope-of-use” have been expanded within the United States and Europe to include refined products and refined products pipelines for the increase in flow rates and the lowering of the Maximum Allowable Operating Pressures (MAOP), both, and to lower energy consumption and costs at the pump stations by allowing some of the pump stations to be shut down and bypassed as a direct result of the DRA use. Slurry-based DRA product has also been expanded to lower energy consumption at the pump stations by allowing some of the pump stations to be shut down and bypassed, and included as design and engineering elements and considerations in the construction of new pipelines and operational options on existing projects and systems throughout the world.
A significant set of requirements is included within the production and sale of slurry-based DRA products to end-user markets within crude oil and refined products pipeline systems. The preferred DRA slurry product must generally include but is not specifically limited to the following general requirements:
1. must be relatively stable and capable of being transported over long distances whether the long trip is a domestic transfer or an international transfer, both without the need of special “in-shipment” agitation or mixing;
2. must possess reasonable “in-storage” stability, including the capability to be stored in bulk volume at the customer use location or other off location storage locations for extended periods of time and within reasonable ambient temperature ranges such that it maintains its product consistency alone or with the assistance of intermediate agitation and/or other physical systems which protect or buffer the slurry product temperature in order to maintain its stability and ability to be reconstituted into its fully functional product form should it be allowed to separate;
3. must not demonstrate the tendency to separate and/or agglomerate into an unrecoverable mass rendering it unusable;
4. must be composed of finely divided polyalphaolefin particles having minimum and maximum particle size distribution which allows for the injection and immediate dispersion of the DRA slurry product polymer within the treated petroleum stream upon entry into the pipeline system;
5. the preferred DRA slurry product used in refined fuels applications (excluding jet fuels) should be composed of solvent and non-solvents and other finely divided polyalphaolefin (“PAO”) particles and particulate or dispersed components which do not negatively impact or harm these refined products and quality of the fuel or the safety and “end use” performance of the fuel at acceptable DRA dosages up to and including a maximum acceptable PAO dosage limit of about 15 ppm (wt/wt.) added to these refined products pipeline system.
It is a focus of the present invention to provide a new family of DRA suspending agents, which are commonly available components that are produced from strategically available alternative production units than the current limited sources of special alcohols, and complex water-alcohol and antifreeze/additive suspending liquids.
The present invention also provides stability from separation between the new suspending agents and DRA polymer solids.
It is another focus of the present invention to provide various specifications and potential embodiments which are more specifically focused on the DRA slurry products and gel forms which would be primarily intended for use in refined products but should not be specifically limited to only such applications. It can be appreciated by those skilled in the art that the DRA slurry products and DRA gel products of the present invention has applications in every field of use applicable to DRA products.
It is, therefore, a feature of the present invention to provide DRA slurry products and DRA gel products.
A feature of the present invention is to provide DRA slurry products and DRA gel products that do not separate into an unrecoverable mass rendering it unusable.
A feature of the present invention is to provide DRA slurry products and DRA gel products that do not agglomerate into an unrecoverable mass rendering it unusable.
Another feature of the present invention is to provide DRA slurry products and DRA gel products that possess reasonable “in-storage” stability.
Yet another feature of the present invention is to provide DRA slurry products and DRA gel products that can be stored in bulk volume at the customer use location or other off location storage for extended periods of time and within reasonable ambient temperature ranges.
Still another feature of the present invention is to provide DRA slurry products and DRA gel products that maintains its product consistency during storage.
Yet still another feature of the present invention is to provide DRA slurry products and DRA gel products that maintain their stability and ability to be reconstituted into its fully functional product form should it be allowed to separate.
Another feature of the present invention is to provide DRA slurry products and DRA gel products that are sufficiently stable and capable of being transported over long distances without the need of special “in-shipment” agitation or mixing.
Still another feature of the present invention is to provide DRA slurry products and DRA gel products that is composed of finely divided polyalphaolefin particles having a minimum and maximum particle size distribution which allows for the injection and immediate dispersion of the DRA slurry product within the treated petroleum stream upon entry into the pipeline system.
Yet still another feature of the present invention is to provide DRA slurry products and DRA gel products that can be used in refined fuels applications that does not negatively impact or harm the refined products or the quality of the refined fuel or the safety and “end use” performance of the refined fuel.
Yet another feature of the present invention is to provide DRA slurry products and DRA gel products that can be used in refined fuels applications at acceptable DRA dosages up to and including a maximum acceptable PAO dosage limit of about 15 ppm (wt/wt.) added to the refined fuel products in a pipeline system.
Yet still another feature of the present invention is to provide DRA slurry products and DRA gel products that reduce the amounts of superfluous components that increase costs and do not contribute to the practical function of the DRA products.
Still another feature of the present invention is to provide DRA slurry products and DRA gel products that reduce the amounts of superfluous components that pose a greater risk of insult to the refined fuel properties, thus inhibiting the ability to raise the acceptable limits of use from the current 15 PPM polymer limits imposed by the refined products pipeline operators and their shippers.
Yet another feature of the present invention is to provide DRA slurry products and DRA gel products that overcome the severe problem of separation between suspending mediums and DRA polymer solids.
Yet still another feature of the present invention is to provide DRA slurry products and DRA gel products that have the characteristics required to be used in arctic conditions.
Still another feature of the present invention is to provide DRA slurry products and DRA gel products that, in some formulations, avoid having noxious odors created by the use of alcohols.
Yet still another feature of the present invention is to provide DRA slurry products and DRA gel products that have a lower cost than the present DRA products that use the higher temperature freeze point vegoils.
Yet still another feature of the present invention is to provide DRA slurry products and DRA gel products that increase the polymer solids loading of the product.
Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will become apparent from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized by means of the combinations and steps particularly pointed out in the appended claims.